#==== EXAMPLE FOR THE codfw -> eqiad SWITCH ====

Executing commands ('mysql --skip-ssl --skip-column-names --batch -e "SELECT ts FROM heartbeat.heartbeat WHERE datacenter = \'codfw\' and shard
= \'s1\' ORDER BY ts DESC LIMIT 1"',) on 1 hosts: db2048.codfw.wmnet
----- OUTPUT of 'mysql --skip-ssl...ts DESC LIMIT 1"' -----
2018-09-06T16:42:37.001790
================
PASS:  |####################################################################################################| 100% (1/1) [00:00<00:00,  3.06hosts/s]
FAIL:  |                                                                                                            |   0% (0/1) [00:00<?, ?hosts/s]
100.0% (1/1) success ratio (>= 100.0% threshold) for command: 'mysql --skip-ssl...ts DESC LIMIT 1"'.
100.0% (1/1) success ratio (>= 100.0% threshold) of nodes successfully executed all commands.



Executing commands ('mysql --skip-ssl --skip-column-names --batch -e "SELECT ts FROM heartbeat.heartbeat WHERE datacenter = \'codfw\' and shard
= \'s1\' ORDER BY ts DESC LIMIT 1"',) on 1 hosts: db1067.eqiad.wmnet
----- OUTPUT of 'mysql --skip-ssl...ts DESC LIMIT 1"' -----
2018-09-06T16:42:50.001530
================
PASS:  |####################################################################################################| 100% (1/1) [00:00<00:00,  1.43hosts/s]
FAIL:  |                                                                                                            |   0% (0/1) [00:00<?, ?hosts/s]
100.0% (1/1) success ratio (>= 100.0% threshold) for command: 'mysql --skip-ssl...ts DESC LIMIT 1"'.
100.0% (1/1) success ratio (>= 100.0% threshold) of nodes successfully executed all commands.



And the later check passed without retries. This because we do first gather all the positions from dc_from and then check dc_to, so some time passes between one and the other.